A superconducting hot-electron bolometer has been built and tested as a prototype of high-sensitivity, rapid-response detectors of submillimeter-wavelength radiation. There are diverse potential applications for such detectors, a few examples being submillimeter spectroscopy for scientific research; detection of leaking gases; detection of explosive, chemical, and biological weapons; and medical imaging.

A Thin Nb Bridge having Tc = 6 K lies between thicker Nb contacts having Tc = 8.6 K that, in turn, are connected to an antenna that couples submillimeter- wavelength radiation into the device.
This detector is a superconducting-transition-edge device. Like other such devices, it includes a superconducting bridge that has a low heat capacity and is maintained at a critical temperature (Tc) at the lower end of its superconductingtransition temperature range. Incident photons cause transient increases in electron temperature through the superconducting- transition range, thereby yielding measurable increases in electrical resistance. In this case, Tc = 6 K, which is approximately the upper limit of the operating-temperature range of silicon-based bolometers heretofore used routinely in many laboratories. However, whereas the response speed of a typical silicon-based laboratory bolometer is characterized by a frequency of the order of a kilohertz, the response speed of the present device is much higher — characterized by a frequency of the order of 100 MHz.